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Replace the old crude event listener system with a much more generic implementation, patterned after the event dispatch techniques used in Google Web Toolkit 1.5 and later. Each event delivers to an interface that defines a single method, and the event itself is what performs the delivery in a type-safe way through its own dispatch method. Listeners are registered in a generic listener list, indexed by the interface they implement and wish to receive an event for. Delivery of events is performed by looping through all listeners implementing the event's corresponding listener interface, and using the event's own dispatch method to deliver the event. This is the classical "double dispatch" pattern for event delivery. Listeners can be unregistered by invoking remove() on their registration handle. This change therefore requires application code to track the handle if it wishes to remove the listener at a later point in time. Event delivery is now exposed as a generic public method on the Repository class, making it easier for any type of message to be sent out to any type of listener that has registered, without needing to pre-arrange for type-safe fireFoo() methods. New event types can be added in the future simply by defining a new RepositoryEvent subclass and a corresponding RepositoryListener interface that it dispatches to. By always adding new events through a new interface, we never need to worry about defining an Adapter to provide default no-op implementations of new event methods. Change-Id: I651417b3098b9afc93d91085e9f0b2265df8fc81 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>stable-0.9
Shawn O. Pearce
15 years ago
12 changed files with 358 additions and 157 deletions
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/* |
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* Copyright (C) 2010, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.events; |
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import java.util.List; |
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import java.util.concurrent.ConcurrentHashMap; |
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import java.util.concurrent.ConcurrentMap; |
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import java.util.concurrent.CopyOnWriteArrayList; |
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/** Manages a thread-safe list of {@link RepositoryListener}s. */ |
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public class ListenerList { |
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private final ConcurrentMap<Class<? extends RepositoryListener>, CopyOnWriteArrayList<ListenerHandle>> lists = new ConcurrentHashMap<Class<? extends RepositoryListener>, CopyOnWriteArrayList<ListenerHandle>>(); |
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/** |
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* Register an IndexChangedListener. |
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* |
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* @param listener |
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* the listener implementation. |
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* @return handle to later remove the listener. |
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*/ |
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public ListenerHandle addIndexChangedListener(IndexChangedListener listener) { |
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return addListener(IndexChangedListener.class, listener); |
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} |
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/** |
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* Register a RefsChangedListener. |
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* |
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* @param listener |
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* the listener implementation. |
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* @return handle to later remove the listener. |
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*/ |
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public ListenerHandle addRefsChangedListener(RefsChangedListener listener) { |
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return addListener(RefsChangedListener.class, listener); |
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} |
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/** |
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* Add a listener to the list. |
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* |
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* @param <T> |
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* the type of listener being registered. |
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* @param type |
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* type of listener being registered. |
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* @param listener |
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* the listener instance. |
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* @return a handle to later remove the registration, if desired. |
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*/ |
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public <T extends RepositoryListener> ListenerHandle addListener( |
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Class<T> type, T listener) { |
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ListenerHandle handle = new ListenerHandle(this, type, listener); |
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add(handle); |
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return handle; |
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} |
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/** |
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* Dispatch an event to all interested listeners. |
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* <p> |
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* Listeners are selected by the type of listener the event delivers to. |
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* |
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* @param event |
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* the event to deliver. |
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*/ |
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@SuppressWarnings("unchecked") |
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public void dispatch(RepositoryEvent event) { |
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List<ListenerHandle> list = lists.get(event.getListenerType()); |
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if (list != null) { |
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for (ListenerHandle handle : list) |
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event.dispatch(handle.listener); |
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} |
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} |
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private void add(ListenerHandle handle) { |
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List<ListenerHandle> list = lists.get(handle.type); |
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if (list == null) { |
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CopyOnWriteArrayList<ListenerHandle> newList; |
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newList = new CopyOnWriteArrayList<ListenerHandle>(); |
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list = lists.putIfAbsent(handle.type, newList); |
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if (list == null) |
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list = newList; |
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} |
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list.add(handle); |
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} |
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void remove(ListenerHandle handle) { |
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List<ListenerHandle> list = lists.get(handle.type); |
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if (list != null) |
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list.remove(handle); |
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} |
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} |
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/* |
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* Copyright (C) 2010, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
|
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
||||
* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.events; |
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/** Describes a change to one or more references of a repository. */ |
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public class RefsChangedEvent extends RepositoryEvent<RefsChangedListener> { |
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@Override |
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public Class<RefsChangedListener> getListenerType() { |
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return RefsChangedListener.class; |
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} |
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@Override |
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public void dispatch(RefsChangedListener listener) { |
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listener.onRefsChanged(this); |
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} |
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} |
@ -0,0 +1,49 @@
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/* |
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* Copyright (C) 2010, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
|
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
||||
* names of its contributors may be used to endorse or promote |
||||
* products derived from this software without specific prior |
||||
* written permission. |
||||
* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
||||
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
||||
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
||||
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
||||
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.events; |
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/** A listener can register for event delivery. */ |
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public interface RepositoryListener { |
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// Empty marker interface; see extensions for actual methods.
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} |
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